This invention relates to a golf club shaft, more particularly to a shaft which has an adjacent pair of enlarged portions defining a contracted section therebetween so as to form two flex points on the shaft.
It is understood that a golf club shaft can act as a resilient rod which is shown in FIG. 1 and which is fixed on the ground. As illustrated in FIG. 2, when a horizontal force (F) is applied to the top end of the rod 11, a restoration force (R) is created on the top end of the rod 11. Referring to FIG. 3, in a case where the rigidity of the golf club shaft is large such that the flex point of the shaft is located on the lower portion 14 of the shaft, the ball struck by the club flies in the direction indicated by the arrow 15 which forms a larger angle with the ground. In this case, the restoration force of the golf club shaft is small, causing limited flying distance of the ball. In contrast, referring to FIG. 4, in a case where the rigidity of the golf club shaft is small such that the flex point of the shaft is located on the upper portion of 16 the shaft, the ball flies in the direction indicated by the arrow 17 which forms a smaller angle with the ground. In this case, the restoration force of the golf club shaft is too large to easily control movement of the ball, thereby causing the need of better professional skill to swing the shaft. Furthermore, upon striking the ball with the club, the vibration of the club is transferred rapidly to the grip and results in relatively uncomfortable feel of the player.